The invention relates to a method for monitoring the quality of spot welds, particularly for robotic applications. The most different systems for assessing the quality of a welding spot have already been known, as is to be taken from EP 0 830 914 B1.
U.S. Pat. No. 3,940,624 A describes a method and a device for monitoring welds by radiating the welding site with an infrared-light source and optically detecting the resulting reflected or transmitted radiation. According to a variant of the described method, a MYLAR film is drawn over the welding site with a liquid crystal and the change in the liquid crystal brought about by the heat radiated from the welding site is optically detected. In doing so, it is disadvantageous that the welding spot itself or the liquid crystal display, which is not stable though, is evaluated, thus necessitating site-related and time-related measurements.